The activities of the oil industry have created serious environmental problems resulting from the intrinsic operations of the processes of exploration, production, refining, distribution and use of hydrocarbons. Hydrogen sulfide (H2S) is a smelly, corrosive, highly toxic gas, which is generated as part of the oil industry activities. Hydrogen sulfide is commonly found in the form of natural gas and is particularly obtained if the oil contains high concentration of sulfur compounds, such as oil in Mexico. Since H2S is a pollutant substance, it seeks to be transformed into elemental sulfur, which has a greater use in the general industry.
Nowadays, the process used for the recovery of H2S in oil activities is known as Claus Process, which has become a standard in the oil industry. Its inventor, the scientist Carl Friendrich Claus patented the Claus process in 1883.
The Claus process involves separating the H2S from the gas stream using an extraction with liquid solutions of various alkyl amines, commonly referred as amines. There are different types of amines which are used in the Claus process, such as monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), diisopropylamine (DIPA), and the ethoxy ethanol amine also known as diglycolamine (DGA); being the MEA, DEA and MDEA, the alkyl amines more used.
In the Claus process, H2S is fed to a Claus unit, resulting in two stages:                a) A thermal stage, where H2S is partially oxidized with air, this occurs in a reaction oven at high temperatures from 1000 to 1400° C., forming elemental sulfur (S) and sulfur dioxide (SO2), but remains H2S unreacted; and        b) A catalytic stage, where the remaining H2S reacts with SO2 at low temperatures, around 200-350° C., over a catalyst to form and depleted in elemental sulfur (S).        
The Claus process uses different types of industrial catalysts, such as titanium oxide catalyst, alumina, zeolites, clays, silico-aluminates, porous, among others.
The H2S deactivates industrial catalysts, such as catalysts of titanium oxide, (TiO2) and others mentioned above. Once exhausted by elemental sulfur (S) and/or deactivated, the catalysts used in the Claus process become polluting and hazardous wastes.
Currently, exhausted and/or deactivated industrial catalysts in the Claus process are disposed in sites established by environmental legislation for the disposal of hazardous wastes, seeking to minimize damages to the environment and ecosystem, but with an environmental impact because they are still hazardous wastes. Moreover, the recovery of elemental sulfur (S) is still missing, which has a greater use in the general industry. Based on the technique state of art, the treatment of catalysts contaminated and/or spent has been basically focused to the recovery of catalysts which contain or may contain different metals such as copper (Cu), iron (Fe), aluminum (Al), nickel (Ni), cobalt (Co), vanadium (V) and molybdenum (Mo).
Regarding catalysts contaminated and/or spent with sulfur, there is no treatment.
The Mexican patent MX 167.308 (B), Mar. 15, 1993 relates to a process for regenerating a catalyst contaminated with sulfur, comprising a zeolite and a Group VIII metal which process is characterized because involves agglomerating the Group VIII metal and subsequently separating the sulfur from the catalyst, with a focus on the chemical treatment of separation of the aforementioned metals.
None of the mentioned references suggest or even less claim bacterial cultures of Acidithiobacillus thiooxidans, their isolation method, maintenance and identification, and their use in the treatment of materials containing sulfur-compounds, such as contaminated and/or spent catalysts with elemental sulfur (S).